2
0
2017
dre
ogi
0
journal
Original
Drebushchak, V. A.
Ogienko, A. G.
Yunoshev, A. S.
Thermochim. Acta
2017
2020-09-29
Metastable eutectic melting in the NaCl-H2O system
Metastable eutectic melting of solid mixture NaCl + H2O was measured in a wide range of its compositions by using a DSC. The new eutectic melting was found to occur near -27.C, below the wellk now ice-NaCl*2H2O eutectic point (-21.1degC, 23.3 wt.%) of equilibrium both phase diagram. The new low-temperature eutectic was detected for all samples, in two-phase regions, H2O-NaCl*2H2O and NaCl*2H2O-NaCl. The new eutectic temperature is close to the value of -28degC reported by Roedder (1984) for the mixture of solid H2O and NaCl, which was never repeated or reaffirmed independently since then. The heat effect of the metastable eutectic melting did allow us to estimate the enthalpy of formation of hydrohalite from salt and ice: NaCl(cr) + 2H2O(cr) = NaCl*2H2O(cr) + DH (-0.73 +- 0.07 kJ mol-1).
DSC
Eutectic
Hydrohalite
Metastable
NaCl-H2O system
10.1016/j.tca.2016.12.004
647
94-100
1
InChI=1S/H2O/h1H2
XLYOFNOQVPJJNP-UHFFFAOYSA-N
water
H2O
1
Commercial source
1
Fractional distillation
2
99.8
3
Estimated by the compiler
2
InChI=1S/ClH.Na/h1H;/q;+1/p-1
FAPWRFPIFSIZLT-UHFFFAOYSA-M
sodium chloride
ClNa
1
Commercial source
1
99
2
Estimated by the compiler
3
InChI=1S/ClH.Na.2H2O/h1H;;2*1H2/q;+1;;/p-1
XZPVPNZTYPUODG-UHFFFAOYSA-M
sodium chloride dihydrate
ClH4NaO2
1
Synthesized by the authors
1
99
2
Estimated by the compiler
1
2
1
1
1
Principal objective of the work
AB
TRC
3/7/2017
1
Eutectic temperature, K
DTA
Crystal
Direct value, X
1
Data file compiler
Propagation of evaluated standard uncertainties
95
Crystal
1
Crystal
2
Liquid
Air at 1 atmosphere
1
246.25
3
1
0.5
2
2
1
1
1
Principal objective of the work
AB
TRC
3/7/2017
1
Eutectic temperature, K
DTA
Crystal
Direct value, X
1
Data file compiler
Propagation of evaluated standard uncertainties
95
Crystal
1
Crystal of intercomponent compound 1
Liquid
Air at 1 atmosphere
1
252.25
3
1
0.5
1
2
1
-1
Crystal
3
1
1
Crystal
1
1
-2
Crystal
Principal objective of the work
AB
TRC
3/7/2017
Other reactions
1
Molar enthalpy of reaction, kJ/mol
DSC
250
2
100
1
1
Data file compiler
Propagation of evaluated standard uncertainties
95
1
-0.73
2
1
0.14